Switching contact arrangement for a power switch

ABSTRACT

The invention relates to a switching contact arrangement for a power switch, which is characterized in that a plurality of contact levers are pivoted on a contact support ( 30 ) by means of a bearing pin ( 37 ) and that the contact support ( 30 ) is provided with at least three support elements ( 32   a   , 32   b   , 31 ) for radially supporting the bearing pin. In order to simplify production of the contact support, at least three of the support elements ( 32   a   , 32   b   , 31 ) are configured as a one-piece shaped element that forms the contact support ( 30 ). At least one of the support elements can have a metal element ( 31 ) that is at least partially embedded in a plastic shaped element ( 43 ) of the contact support ( 30 ). Said metal element ( 31 ) can be configured as a sheet metal part.

This application is the national phase under 35 U.S.C. § 371 of PCTInternational Application No. PCT/DE02/01250 which has an Internationalfiling date of Mar. 28, 2002, which designated the United States ofAmerica and which claims priority on German Patent Application numbersDE 101 17 844.1 filed Apr. 4, 2001 and DE 201 18 493.1 filed Nov. 7,2001, the entire contents of which are hereby incorporated herein byreference.

FIELD OF THE INVENTION

The invention generally relates to the field of electrical/powerswitches, and is preferably applicable to the design configuration of arigid member which is used as a contact mount for a contact.

BACKGROUND OF THE INVENTION

In a known electrical switch of this type, in which two or more contactlevers which form the contact are held on the contact mount by way of abearing bolt such that they can pivot, the contact mount has at leastthree supporting elements in order to support the bearing bolt radially(E 0 222 686 B1). The contact mount in this case includes a metal frame,which is formed from two side walls and from two or more bolts whichconnect the side walls. The metal frame is hinged via a coupling bolt onan insulating coupling element, which is used for coupling the contactmount to a switch drive. Two of the supporting elements, which areassociated with the ends of the bearing bolt, are in this case formed bythe side walls of the metal frame.

In order to prevent undesirable radial bending of the bearing bolt forthe contact levers with as little complexity in terms of additionalmaterial as possible, two intermediate bearings for this contact mount,which are arranged between adjacent contact levers in the axiallycentral region of the bearing bolt, form additional supporting elementsby being hinged on the coupling bolt. In this case, aperture openingsare required for the contact mount, for the intermediate bearings topass through to the coupling bolt. Supporting elements which areintegrated in this way in addition to the two outer supporting elementsin the contact mount must be positioned for installation of the bearingbolt, owing to their capability to pivot about the coupling bolt.

SUMMARY OF THE INVENTION

Against the background of an electrical switch, an embodiment of theinvention is based on an object of simplifying the production andinstallation of the contact mount.

According to an embodiment of the invention, an object may be achievedin that at least three of the supporting elements are in the form ofpart of a molding which forms the contact mount and is producedintegrally. For the purposes of an embodiment of the invention, theexpression an integrally produced molding should be understood as beinga part in which two or more functional elements are connected in thecourse of a molding process, such as a stamping, injection-compressionmolding, casting, injection molding, compression molding or sinteringprocess, to form a single component which is assembled such that itcannot be disconnected for installation purposes.

In the case of a refinement such as this, the three supporting elementsare integrated rigidly in a predetermined position in the contact mount,as part of it. In this case, the three supporting elements are actuallyaligned with the axis of the bearing bolt during the production of thecontact mount so that no tilting of the bearing bolt caused by tolerancediscrepancies will in practice occur during operation of the switch. Abearing bolt which is supported in this way is also subject to only asmall maximum amount of bending when high short-circuit or surgecurrents occur, and thus has a good capability to withstand highshort-circuit and surge currents.

The novel switching contact arrangement may have a large number ofcontact levers, which are each subject to an individual tolerancediscrepancy from a given nominal size, and intermediate bearings, whichare possibly likewise subject to an individual tolerance discrepancyfrom their nominal size, but which may be part of the contact levers,since the number of contact levers is subdivided into subsets. Each ofthese is arranged axially bounded between two adjacent supportingelements. This axial bounding of the subsets of contact levers limitsany axial movement of the contact levers in one subset, owing to thecurrent forces which act between them, to the axial section of thebearing bolt which is bounded by the respective supporting elements. Themaximum amount of movement is not greater than the sum of all theindividual tolerance discrepancies of the contact levers and of theintermediate bearings, which may be present, in this subset. This makesit possible to geometrically associate the contact levers with contactforce springs such that their spring force is not reduced by bending ortilting. The geometrically accurate association between the contactforce springs and the contact levers thus also contributes to increasingthe capability of the switching contact arrangement to withstandshort-circuit and surge currents.

If the molding is at least partially in the form of a plastic molding,then there is no need for the coupling bolt to have an electricallyinsulating configuration. The mechanical strength of a plastic moldingsuch as this can be increased by embedding at least one reinforcementelement at least partially in the plastic molding. A thermosettingplastic which, for example, has fiber reinforcement is typically usedfor the plastic molding and a nonmagnetic steel, for example, is usedfor the reinforcement element. As an alternative to this, other pureplastics or, for example, plastics reinforced by ceramic or glass fiberscan also be used for the plastic molding, and other metals or metalsheets can be used for the reinforcement element.

One preferred refinement of the novel switching contact arrangementprovides for at least one of the supporting elements to have a metalpart which is at least partially embedded in the plastic molding.

A metal part such as this may be part of the reinforcement element, thusat the same time increasing the mechanical strength of that part of thecontact mount which forms the supporting element.

If the metal part is in the form of a metal sheet, for example composedof nonmagnetic sheet steel, a first subregion of which, which hasundercuts, is embedded in the plastic molding and a second subregion ofwhich, which is provided with a hole for the bearing bolt, projects outof the plastic molding. This then advantageously allows the crosssection of the supporting element to be reduced such that it is nobroader than the distance between the contact levers that is requiredfor separation of the contact levers and thus does not lead to anyadditional broadening of the contact mount.

A further advantageous refinement of the novel switching contactarrangement provides for supporting elements which contain the metalparts to be at a distance from the coupling element in the axialdirection of the bearing bolt if the contact mount is coupled to aswitching shaft, which can be rotated using a switch drive, via ametallic coupling element. This makes it possible to avoid accidentalenergizing and problems relating to the insulation between the contactmount and the switch drive, in a simple manner. In this refinement, theentire available material depth of the contact mount transversely withrespect to the bearing bolt can be used for the rigid embedding of afirst subregion of a supporting element which is in the form of a metalsheet.

If a holder for the shielding body is provided on at least one of thesupporting elements for a contact mount which is equipped with theshielding body, then this provides additional support for the shieldingbody against the gas pressure which occurred during switching. In arefinement such as this, side mounting limbs, which rest on the contactmount, are designed to be smaller owing to the reduced load, or maypossibly be omitted.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description of preferred embodiments given hereinbelow and theaccompanying drawings, which are given by way of illustration only andthus are not limitative of the present invention, wherein FIGS. 1 to 9show a number of exemplary embodiments of the novel switching contactarrangement and wherein:

FIG. 1 shows a schematic section illustration of a low-voltage circuitbreaker with a switching contact arrangement which comprises astationary contact assembly and a moving contact assembly,

FIG. 2 shows a moving contact assembly with a first embodiment of acontact mount which is at least partially in the form of a plasticmolding,

FIG. 3 shows a reinforcement element, which may be embedded in theplastic molding of the contact mount shown in FIG. 2,

FIG. 4 shows a second embodiment of a contact mount which is at leastpartially in the form of a plastic molding, and in which supportingelements in the form of a metal sheet are partially embedded in theplastic molding,

FIG. 5 shows a section illustration, transversely with respect to thedirection of the bearing bolt, through the contact mount shown in FIG.4,

FIG. 6 shows a reinforcement element which may be embedded in theplastic molding of the contact mount in FIG. 4,

FIG. 7 shows a section illustration, transversely with respect to thedirection of the bearing bolt, through a contact mount with an embeddedreinforcement element as shown in FIG. 6,

FIG. 8 shows a further section illustration through the contact mountillustrated in FIG. 4 along the line A-A in FIG. 5, and

FIG. 9 shows the contact lever mount as shown in FIG. 4 with a shieldingbody.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The electrical switch which is shown in FIG. 1 and is used inlow-voltage power supply systems for voltage ranges up to about 1 000 Vhas a switch pole enclosure 1 in which switching chambers 2 are formedalongside one another, depending on the number of poles required. Aswitching shaft 4, which can be rotated by way of a switch drive 3, isused to operate the switching contact arrangement jointly, each of whichincludes a stationary contact assembly 5 and a moving contact assembly6. For this purpose, two levers 7 which project radially from theswitching shaft 4 (see FIG. 8) are coupled to a metallic couplingelement which is hinged on the moving contact assembly 6. The contactassemblies 5, 6 are connected in a known manner to externally accessibleconnecting rails 9, 10. Two exemplary embodiments 6 a and 6 b of themoving contact assembly 6 will be explained in the following text withreference to FIGS. 2 and 3 and, respectively, FIGS. 4 to 9.

As can be seen in more detail from FIG. 2, the moving contact assembly 6a has a contact mount 11 which has a plastic molding 12 in the form ofan integrally produced molding, which was formed in the course of astamping process, with a reinforcement element as shown in FIG. 3 beingembedded in it. The contact mount is mounted in the enclosure 1 (seeFIG. 1) such that it can pivot, and can be moved via the switching shaft4 and by use of the switch drive 3, of which FIG. 1 shows only one driverun 15 that is supported on a spring stalk 14 relative to the stationarycontact assembly 5 to a connected position and to a disconnectedposition.

Two or more contact levers 16, 17, which are arranged parallel to oneanother, on the contact mount 11 can pivot relative to the contact mount11 about a bearing bolt 18. Contact force springs 19 (see FIG. 1) ensurethat the contact levers 16, 17 are prestressed in the direction of thestationary contact assembly 5. Flexible conductors 20 in the form ofbraids or strips are used for connecting the contact levers 16, 17 tothe lower connecting rail 10 in such a way as to guarantee that thecontact levers 16, 17 and the contact mount 11 can move without anyimpediment during the switching movements.

The number of contact levers 16, 17 which are fitted to the contactmount 11 depends on the magnitude of the current which the circuitbreaker is intended to carry during operation. As can be seen from FIG.2, of the total of 22 contact levers that are provided, 8 contact levers16 are designed to be shorter and have only one contact area 21, whichhave no leading contact area 22 and no arcing horn 23 in the same way asthe other contact levers 17.

During operation, all the contact levers are held between side pieces 24a, 24 b of the contact mount 11, which point transversely with respectto the bearing bolt 18. These side pieces 24 a, 24 b, which are providedwith holding openings 25 a, 25 b for the bearing bolt 18 form a firstand a second supporting element for the ends of the bearing bolt, viawhich the bearing bolt is positioned axially and is supported radially.A part 29 a or 29 b of the reinforcement element 13 (see FIG. 3) canextend in each of these side pieces, and has an aperture 27 a or 27 b,respectively, for the bearing bolt. In the downward direction, the sidepieces 24 a, 24 b merge into bearing arms 26 for the contact mount 11.

The relatively large width of the switching contact arrangementindicates that the section of the bearing bolt which runs between thetwo side supporting elements 24 a, 24 b is subjected to a relativelysevere bending load when further forces in addition to the forces of thecontact force springs 19 are caused by a heavy current, such as ashort-circuit or surge current, when the switching contact arrangementis in the closed state.

Bending of this section of the bearing bolt is prevented by way of anadditional, third supporting element, which supports the bearing boltaxially in the center. This third supporting element is formed by acontact mount rib 28, which is provided with a holding opening 25 c(which cannot be seen in the figure) for the bearing bolt 18 and pointstransversely with respect to the bearing bolt, with a metal part 29 c(which is completely embedded in the plastic molding 12 and has anaperture 27 c for the bearing bolt) extending in the rib 28 and beingpart of the reinforcement element 13 (see FIG. 3).

Of the second exemplary embodiment 6 b of the moving contact group, FIG.4 shows only a second embodiment 30 of the contact mount. In thiscontact mount 30, two supporting elements, which are in the form ofmetal sheets 31, are used to radially support that section of thebearing bolt which runs between two supporting elements that are in theform of side pieces 32 a, 32 b. A first subregion 33 of the two centralsupporting elements 31 is embedded in the plastic molding 34 of thecontact mount 30, and together with a second subregion 35 of the twocentral supporting elements 31, projects out of the plastic molding.

As can be seen in FIG. 5, the metal sheets 31 have undercuts 36 in thefirst subregion 33 which is embedded in the plastic molding, and theseare used to anchor the respective metal sheet in the plastic moldingsecurely even when the bearing bolt is subjected to a high bending load.The second subregion 35, which is provided with a hole 38 for thebearing bolt 37 to pass through, also has a recess 39, which is used tohold a shielding body 40 that is not shown in any more detail in FIG. 9.As is shown in FIG. 7, two reinforcement elements 41, 42 may be embeddedin the plastic molding of the contact mount, and one of these isillustrated in FIG. 6.

As can be seen from FIG. 8, the two metal sheets 31 are at a distancefrom the metallic coupling element 8 (see FIG. 1) in the axialdirection, in order to avoid accidental energizing between the bearingbolt (which is at a low-voltage potential) of the contact levers and themetallic coupling element 8 (which is at ground potential), and thus theswitch drive.

As can be seen from FIG. 9, tongues 43 are integrally formed on theshielding body 40, which protects the pivoting area of the contact mount30 and further switch parts (which are not shown in any more detail butare arranged underneath the contact areas 21, 22 (see FIG. 1)) againsterosion products that fall out and against condenser switching gases,and these tongues 43 engage in the recesses 39 which are provided on themetal sheets (see also FIG. 5). In consequence, the shielding body 40 issupported against the gas pressure which occurs during switchingprocesses, in such a way that its mounting limbs 44 a, 44 b, which areheld in the side on the contact mount, are less severely loaded.

Exemplary embodiments being thus described, it will be obvious that thesame may be varied in many ways. Such variations are not to be regardedas a departure from the spirit and scope of the present invention, andall such modifications as would be obvious to one skilled in the art areintended to be included within the scope of the following claims.

1. A switching contact arrangement for an electrical switch, comprising:a contact mount; at least two contact levers, pivotably attached to themount via a bearing bolt, wherein the contact mount includes at leastthree supporting elements adapted to radially support the bearing bolt,and wherein at least three of the supporting elements are producedintegrally in the form of at least part of a molding forming the contactmount.
 2. The switching contact arrangement as claimed in claim 1,wherein the molding is at least partially in the form of a plasticmolding.
 3. The switching contact arrangement as claimed in claim 2,wherein at least one metallic reinforcement element is at leastpartially embedded in the plastic molding.
 4. The switching contactarrangement as claimed in claim 2, wherein at least one of thesupporting elements has a metal part which is at least partiallyembedded in the plastic molding.
 5. The switching contact arrangement asclaimed in claim 4, wherein the metal part is in the form of a metalsheet, a first subregion of which, including undercuts, is embedded inthe plastic molding, and a second subregion of which, provided with ahole for the bearing bolt, projects out of the plastic molding.
 6. Theswitching contact arrangement as claimed in claim 4, wherein, when thecontact mount is coupled to a switching shaft via a metallic couplingelement, the supporting elements which contain a metal part are at adistance from the coupling element in the axial direction of the bearingbolt.
 7. The switching contact arrangement as claimed in claim 2,wherein when the contact mount is equipped with a shielding body on atleast one of the supporting elements, a holder is provided for theshielding body.
 8. The switching contact arrangement as claimed in claim3, wherein at least one of the supporting elements has a metal partwhich is at least partially embedded in the plastic molding.
 9. Theswitching contact arrangement as claimed in claim 8, wherein the metalpart is in the form of a metal sheet, a first subregion of which,including undercuts, is embedded in the plastic molding, and a secondsubregion of which, provided with a hole for the bearing bolt, projectsout of the plastic molding.
 10. The switching contact arrangement asclaimed in claim 5, wherein, when the contact mount is coupled to aswitching shaft via a metallic coupling element, the supporting elementswhich contain a metal part are at a distance from the coupling elementin the axial direction of the bearing bolt.
 11. The switching contactarrangement as claimed in claim 8, wherein, when the contact mount iscoupled to a switching shaft via a metallic coupling element, thesupporting elements which contain a metal part are at a distance fromthe coupling element in the axial direction of the bearing bolt.
 12. Theswitching contact arrangement as claimed in claim 9, wherein, when thecontact mount is coupled to a switching shaft via a metallic couplingelement, the supporting elements which contain a metal part are at adistance from the coupling element in the axial direction of the bearingbolt.
 13. The switching contact arrangement as claimed in claim 3,wherein when there is a contact mount equipped with a shielding body onat least one of the supporting elements, a holder is provided for theshielding body.
 14. The switching contact arrangement as claimed inclaim 4, wherein when there is a contact mount equipped with a shieldingbody on at least one of the supporting elements, a holder is providedfor the shielding body.
 15. The switching contact arrangement as claimedin claim 5, wherein when there is a contact mount equipped with ashielding body on at least one of the supporting elements, a holder isprovided for the shielding body.
 16. The switching contact arrangementas claimed in claim 6, wherein when there is a contact mount equippedwith a shielding body on at least one of the supporting elements, aholder is provided for the shielding body.
 17. A switching contactarrangement for a switch, comprising: at least two contact levers,pivotably attached to a contact support via a bearing pin, wherein thecontact support includes at least three elements adapted to radiallysupport the bearing pin, and wherein at least three of the elements areconfigured as a one piece shaped element forming the contact support.18. The switching contact arrangement as claimed in claim 17, whereinthe one piece element is at least partially formed as a plastic molding.19. The switching contact arrangement as claimed in claim 18, wherein atleast one metallic reinforcement element is at least partially embeddedin the plastic molding.
 20. The switching contact arrangement as claimedin claim 18, wherein at least one of the supporting elements includes ametal part which is at least partially embedded in the plastic molding.21. The switching contact arrangement as claimed in claim 20, whereinthe metal part is in the form of a metal sheet, a first subregion ofwhich, including undercuts, is embedded in the plastic molding, and asecond subregion of which, provided with a hole for the bearing pin,projects out of the plastic molding.
 22. The switching contactarrangement as claimed in claim 20, wherein, when the contact mount iscoupled to a switching shaft via a metallic coupling element, thesupporting elements which contain a metal part are at a distance fromthe coupling element in the axial direction of the bearing pin.
 23. Theswitching contact arrangement as claimed in claim 18, wherein when thecontact mount is equipped with a shielding body on at least one of thesupporting elements, a holder is provided for the shielding body.